CHLOROPHYLL AND PLANKTON OF THE GULF COASTAL WATERS OF SAUDI ARABIA BORDERING

As on land, plants are the real producers in the sea, and on them depend all marine living resources and the basic sustainability of ecosystems. Primary production is performed by chlorophyll-bearing plants ranging from the tiny phytoplankton to the giant kelps through the process of photosynthesis. Zooplankton play an important role as secondary producers and together with phytoplankton they support the vast assemblages of marine food chain with all their diversity and complexity. Data on chlorophyll pigments, phytoplankton and zooplankton are regarded as a sound basis for environmental appraisal of ecosystems. This paper presents and discusses a set of data collected from the Saudi Arabian coastal waters near the desalination plants in AI-Jubail. Materials were collected from six different sites covering the intake and discharge zones during cruises carried out in 1997-98. Analyses of Chlorophyll pigments were made using the spectrophotometric method. Plankton samples were collected using a Nansen plankton net of 75µ mesh size, and analyzed following standard procedures. Chlorophyll a,b,c and Phaeophytin are the most commonly occurring pigment in seawater. Their concentrations showed wide fluctuation. The phytoplankton community was composed of 35 genera representing the Diatoms, Dinoflagellates and Blue- green algae. Zooplankton was composed of Protozoa, Coelentrata,Ctenophora, Aschelminthes, Annelida, Mollusca, Arthropoda, Echinodermata and Chordata. Arthropoda, represented by Cladocera, Copepoda and Crustacean larvae, formed the largest group followed by Chordata. The distribution of phyto and zooplankton are examined and discussed on a seasonal, annual and inter annual basis. In terms of species, over all species composition has not been affected b